Abstract
In the semi-natural grasslands of Aso region,the vegetation has historically been maintained through artificial treatments such as controlled burn. In several grasslands location,however, these burns have been discontinued recently due to labor shortages. Therefore,we compared the vegetation where controlled burns have been stopped and that of grasslands where burns are still performed. For our study,we selected five Miscanthus-grasslands sites:one site where controlled burns continue,and four discontinued-burn sites that vary depending on when controlled burns were stopped (one year ago,six years ago, eight years ago,and approximately thirty years ago). In all five investigatory sites,the community coverages were almost 100%, with community heights between 110-178cm. We observed a higher number of plant species in the site where controlled burns were still practiced compared to the sites where the practice has been discontinued. Where controlled burns had been stopped,the standing dead litter were calculated to be 3 to 8 times that found in the controlled-burn site. The litter were seen to be between 162-602g/m^2 in the stopped-burn areas,while such matter was rare where controlled burns were still performed. In the discontinued-burn grasslands,we found lower coverage,weight and number of stems of Miscanthus sinensis than that found in continued-burn area. The degree of succession (DS) in the discontinued-burn grasslands area tended to be higher than that in the continued-burn area. Species diversity,H',was lowest in the area where burning was stopped one years ago,with H'tending to be higher as the period of burn discontinuance increased. In the mentioned above,it was cleared that stopped-burn made standing dead litter increased temporarily,and it was suggested that vegatation of the semi-natural grassland where controlled burns have been stopped changed to forest gradually.
